Flightradar24 has a fantastic primer on what tech is used to track aircraft, and what it's limitations are: http://www.flightradar24.com/how-it-works http://www

Flightradar24 has a fantastic primer on what tech is used to track aircraft, and what it's limitations are: http://www.flightradar24.com/how-it-works http://www.flightradar24.com/how-it-works